A prior art magnetic disk drive 10 as illustrated in FIG. 1 a slider 13 containing magnetic transducers for reading and writing (not shown) magnetic transitions is urged toward the rotating disk 16 by a suspension (not shown). As the disk rotates an air-bearing develops under the slider and causes it to fly. The distance between the slider and the disk surface is the fly-height (FH). The term “air-bearing height” is used interchangeably with fly-height. The disk 16 typically includes a thin film overcoat 17 and a set of thin films 18 which include one or more ferromagnetic layers in which information is recorded. A disk drive can contain multiple disks and multiple sliders. The slider 13 contains heater 14 which is used to affect the fly-height of the slider by causing a local thermal expansion of the slider in the area where the read and write heads are located. The thermal expansion has the effect of pushing the heads closer to the disk and reducing the effective fly-height. A lower slider fly-height is required for higher areal densities. Fly-heights of less than 7 nm are currently needed. Each slider heater has an adjustable power control element (not shown) in series with it.
The manufacturing process for disk drives with thermal fly-height control includes a calibration process for the control loop for the thermal fly-height control can require a larger amount of heater power than is needed for normal operation. For example, it can be advantageous to over drive the heater to cause contact with the disk. However, the extra power requires a higher voltage supply to the power control element in series with the heater and when not being used results in a higher heat dissipation in the power control element.
In U.S. patent application 2003/0174430 by Takahasi, et al. a disk drive with heaters in the slider is described. The heaters include a heating coil and a thermal expansion element. Two heaters are disposed on opposite sides of the heads. A temperature sensor near the heads is included. The heating coils are electrically connected through the wirings disposed in the arm assembly to a power source and the control unit. Current is supplied from the power source to the coils under control of the control unit. The control unit has a fly-height detection unit, a fly-height control unit, a power supplying control unit, and a converting unit.
In U.S. patent application 2003/0035237 by Jeffrey Lille Feb. 20, 2003 an electro-thermal micromechanical actuator on a slider is disclosed. A movable member is etched into a face of a slider opposite the air-bearing surface of the slider. The movable member is substantially freestanding in relation to the slider, having only a single end connected to the slider. An electrically actuated heater element with two parallel current paths is disposed on the movable member. One of the current paths is substantially narrower than the other current path. When a current is passed through the heater element, the narrower current path heats up more quickly than the wider current path. By varying the current passed through the heater element in a selected manner, a distortion of the movable member is harnessed and used to create a relative motion in the slider body, allowing the slider to be quickly and exactly located over the centerline of a track of a storage device.
In U.S. patent application 2004/0027728 by Coffey et al. Feb. 12, 2004 a magnetic head for thermally-assisted writing of data to a disk is disclosed. In one embodiment, the magnetic head includes a write head element and a heating element which is a resistive infared radiator. The heating element is coupled to at least one via pad which is exposed on an outer surface of the magnetic head. The heating element is formed beneath or within the pole tip such that it is able to transfer heat to a portion of the disk before the write head element can write data to it.